Making chocolate is pretty fascinating thing, but the complexity of the process demands a lot of devotion (if you want to make good chocolate) and quite a number of machines and know-how. The second is especially true if you want to scale things up to make them more efficient and in the end: cheaper. The combination of both is probably the reason while there is a frightening low number of actual chocolate producers out there. Currently the biggest chocolate producer is Barry Callebaut which meanwhile processes more than 30% of the world’s chocolate1 (they also deliver for example Nestlé and Hershey, but also hundreds of smaller producers where many people would expect more artisan-like production methods…).
Fortunately, recent years brought an opposing trend in the high-quality chocolate sector: bean-to-bar. This litterally means that a producer starts from dried chocolate beans to finally produce his own chocolate. For the producer this has the huge advantage of having much more control over the final flavor and texture of the chocolate. While very few traditional chocolate makers have produced their own chocolates for decades2 , the number of small-scale bean-to-bar chocolate makers increased notably over the past few years. But what does that mean?

Illustration showing the chocolate making process. Click image to enlarge.

First back to the basics. Cocoa beans are in principle the seeds of the fruit from cocoa trees (theobroma cacao) which grow in tropical regions not too far from the equator. Much of what most would consider being chocolate flavors only starts to develop during fermentation of the beans. The cocoa beans are surrounded by the pulp which among others contains sugar. To ferment the cocoa beans they are simply left together with the pulp for several days. Some people describe fermentation as controlled rotting which sounds little appetizing, but is in essence correct. Fermentation is a very complex process and involves the presence of microorganisms such as yeasts and bacteria. The unreasoned fear of ‘microorganisms’ in general and the need of precise control in industrial mass production led to a severe decline of fermentation processes in our daily food3. This is clearly a pitty, since fermentation is maybe THE source of some of the most complex flavor profiles we know of. Think of wine, beer, cheese, many teas, traditional bread… and yes: chocolate! The moistness and sugar content of the pulp makes sure that certain microorganisms proliferate which in the end leads to a very complex alteration of the initial product4.
The oversimplified basic scheme is that first yeasts convert the sugar of the pulp into alcohol which is then converted by bacteria into acid. This is very analogous to making first wine and later vinegar out of grapes. The acid produced in the pulp penetrates, and thereby biologically ‘kills’, the beans and triggers very complex biochemical reactions that create many of the cocoa flavor precursors and strongly lower the concentration of other chemical compounds. Here, complex also means that the reaction is absolutely not yet understood in full details!5 What is clear though, is that the beans lose a lot of their bitterness and astringency and brownish6. Further a part of the cocoa proteins is converted into free amino acids which together with sugar molecules form the chemical basis of a lot of flavor development steps the most pronounced of which probably is the Maillard reactions during later roasting. The variety and growth conditions of the beans together with their fermenting is arguably the biggest contribution to the beans’ potential to develop a certain flavor profile.
Fermentation is than stopped when beans are dried, which also makes the beans ready for storage and transport7 . Unless for those in fear of heated food, roasting the dried beans represents the second key step after fermentation to develop the complex chocolate flavors. Roasting converts many compounds that were created during fermentation (which is why people speak of ‘flavor precursors’) into a wide range of typical cocoa flavors8. In total more than 600 different aroma components have been found in chocolate which already gives a good feel for where the very complex flavor profile of high-quality chocolate comes from.
Roasting is certainly the key step for many bean-to-bar chocolate makers because the way of roasting has a lot of influence on the final flavor profile. In general, roasting can create a lot of flavors but does so in two different ways. On the one hand roasting enhances what is sometimes called the cocoa flavors, but on the other hand the process also produces distinct roast flavors that can become very dominating after heavy roasting. Roasting also reduces the chocolate’s acidity. Hence in most cases, mild roasting leads to a more acidic chocolate with only mild roast flavors, while intense roasting shifts the balance more towards the roasting flavors9 that also tend to have less acidity.
Roasting is followed by a series of mostly mechanical steps. The beans are broken and the shell is removed. The remaining cocoa ‘nibs’ contain about 50% cocoa butter and 50% cocoa solids and are ground until they release the cocoa butter and form a homogeneous mass (cocoa mass or chocolate liquor). The degree to which the cocoa mass is ground is very important for the resulting texture. The cocoa solids in the mass remain perceivable if they remain in average larger than about 25µm, which gives a grainy texture10. Sometimes grinding is divided in separate rough grinding and refining steps. Either during grinding or in-between grinding and refining sugar, and for milk chocolate milk powder, is added. Fairly often, a small amount of extra cocoa butter and/or lecithin is added to achieve a smoother, creamier texture.
In practically all cases the refined cocoa mass with added sugar (and milk powder for milk chocolate) is conched. During conching the liquid chocolate is stirred at elevated temperatures typically between 50 and 80°C. Conching has two main effects. First, the mixing which is done in a way that locally induces high sheer forces, has a severe effect on the chocolate texture. During the typically 6 to 72 hour long process, cocoa flavors are partially transferred from the cocoa solids and the cocoa butter to the sugar surface. This clearly changes the flavor perception. Conched chocolate also has a smoother and creamier texture. The second effect of conching is a change of the flavor composition. The temperature is typically too low to drive strong chemical reactions as in the case of roasting. But since the chocolate is kept warm and mixed for a long time, a substantial fraction of the more volatile flavor compounds leaves the chocolate. In many cases this is a desired effect because some of these volatile flavors are considered ‘off-flavors’ (such as acetic acid which is one of causes of the astringency of chocolate). However, this also remains a question of what desired chocolate flavors are. The common dogma in the chocolate world is that conching is a MUST for a ‘correct’ chocolate flavor. Yet some chocolate makers have even started to skip conching altogether. You should definitely taste one of these chocolates made by Claudio Corallo. Yes, their flavor profile is quite different compared to ‘correct’ chocolate. But instead of suffering from all those ‘off-flavors’ I was totally thrilled by its rich and complex fruitiness. Corallo’s chocolate is hence carrying a very clear message: There are a lot of things worth questioning in chocolate making!

And after conching? Still reading? We’re nearly done… After conching (or if you are Corallo one step earlier), the chocolate flavor is ready. It only needs to be tempered which is a procedure to make sure that the cocoa butter becomes solid in the right way. Finally, the tempered chocolate is poured into molds where the chocolate becomes a shiny solid and ready to eat… cheers.

Typically the pulp contains around 85% water with 10-15% sugar [Beckett, 2009]. [↩]

To get some more insight, you can also have a look at [Beckett, 2009]. [↩]

An overly bitter dark chocolate can hence be a sign of an incomplete fermentation process as sometimes the case for cheaper chocolate. [↩]

Beans are often dried in sun dried down to 7-8% water content which prevents molds from growing and makes the beans stable for a long time… actually some of the bulk chocolate beans lie around for years before usage [↩]

One important class are Amadori compounds which are a made of sugar and an amino acid during fermentation. [↩]

For me, one of the best examples to taste this are many of the chocolates from ‘Prallus’ which are often heavily roasted. [↩]

Hi!
I’m currently writing my BSc Food Science thesis on cacao. I found your illustration lovely; is it okay if I use it in my proposal? I added your site as the source, of course. Please let me know if you’d prefer me not to use it, and I’ll immediately remove it
Thanks!
Suzi

Hello
We are a small chocolate maker in Canada. We make a bean to bar chocolate and I was wondering if we could use your diagram (with credit given) to help children understand the process. You have done a wonderful job explaining the process. Thank you for considering